This article is an excerpt from the book I wrote with Jim McLean called, "The Ultimate Guide to TrackMan Swing Analysis.” For more information about purchasing the book, click here.
Spin Loft on Ball Flight Curve
Another factor that influences the ball flight curve is SPIN LOFT, which is the difference between ATTACK ANGLE and DYNAMIC LOFT. We know that SPIN LOFT determines the SPIN RATE, but most people don’t know how it can also increase or decrease the SPIN AXIS. To better explain this concept, we will examine the d-plane.
The picture below shows a side-by-side comparison of two d-planes with roughly the same FACE TO PATH. The DYNAMIC LOFT is reduced on the right, which reduces the SPIN LOFT. By reducing the SPIN LOFT, and maintaining the same FACE TO PATH, the red line (d-plane) tilts more to the right.
You can imagine the left scenario as a 6 iron and the right scenario as a driver. This will help you visualize why a driver curves more than a 6-iron given the same FACE TO PATH. Most golfers assume a drive travels further offline because the ball stays in the air longer. That is partly true, but SPIN LOFT influences curve to a greater degree. In simple terms, as SPIN LOFT decreases, the tilt in the SPIN AXIS increases.
We are not immediately advocating an increase in SPIN LOFT if you’re curving the ball too much because a low SPIN LOFT is critical to long drives. It improves SMASH FACTOR, BALL SPEED, and SPIN RATE. However, when you combine a low SPIN LOFT with a high FACE TO PATH, you have a recipe for more curve than anticipated. This puts more pressure on good timing in order to hit the green or keep the ball in the fairway. To remedy the problem, we recommend reducing FACE TO PATH as much as possible in order to maintain a low SPIN LOFT. We also recommend referencing our SPIN LOFT safety zones in Level 3 to know what numbers to look for.
To better understand the influence of SPIN LOFT on ball flight curve, I ran some tests using Trackman’s ball flight calculator on Trackman University. The following chart examines varying SPIN LOFT numbers with a driver when there is a constant CLUB SPEED and FACE TO PATH. When reducing the SPIN LOFT, I alternated between the ATTACK ANGLE and DYNAMIC LOFT. The Trackman calculator would not exceed a SPIN AXIS of 20 degrees, which is why there is missing data under SIDE when SPIN LOFT was lowered beyond 10 degrees.
The results show a correlation between SPIN LOFT and SPIN AXIS tilt. In other words, as SPIN LOFT decreases, the SPIN AXIS increases even when FACE TO PATH stays the same. When comparing 10 degrees of SPIN LOFT with 14 degrees of SPIN LOFT, we see a 9-yard difference in SIDE. That’s not an incredible amount, but it could make the difference between hitting or missing a fairway.
Golfers with a low SPIN LOFT are those that compress the ball very well, which is typically reserved for advanced players. You can identify this type of golfer when there is a lot of shaft lean at impact causing abnormally low DYNAMIC LOFT numbers. This golfer may also have a very shallow ATTACK ANGLE. The immediate remedy is to work on drills that lesson the FACE TO PATH. That way the advanced golfer can maintain a low SPIN LOFT. If results do not improve, an increase in SPIN LOFT may help. We know a loss in distance is expected when you increase SPIN LOFT, but you might want to consider a small tradeoff if accuracy is your weakness. In other words, if losing a few yards in CARRY means you’re going curve the ball less and hit a few more fairways, increasing the SPIN LOFT may be right for you.
With a driver, a negative ATTACK ANGLE can be a great remedy to increase accuracy because a negative ATTACK ANGLE requires more DYNAMIC LOFT at impact, and more SPIN LOFT to launch the ball optimally. In other words, the higher SPIN LOFT would help reduce the SPIN AXIS tilt. That means there is some science behind why hitting down on the ball with a driver will help you hit more fairways. Try experimenting with the Trackman Optimizer. You will learn that a negative ATTACK ANGLE increases the optimal SPIN LOFT range. Most people see this as a bad thing because you could lose some compression and increase the spin, however, a higher SPIN LOFT may be right for you if you’re seriously struggling with ball flight curve.
Another remedy to improve accuracy is to play a fade instead of a draw. That’s because an open FACE TO PATH often increases the DYNMAMIC LOFT and SPIN LOFT. This will help reduce the SPIN AXIS when there is a FACE TO PATH difference. If you look at the PGA TOUR, it’s no surprise why several players prefer a fade for better control. This is additional science behind why playing a fade could make you more accurate.
Long drive competitors need to understand the relationship between SPIN LOFT and ball flight curve more than anyone. That’s because they produce extraordinarily low SPIN LOFT numbers when they compete. This helps them compress the ball and reduce spin, but when you combine a very low SPIN LOFT with a FACE TO PATH difference, that’s a recipe for a lot more curve than expected. Looking back at the chart, a SPIN LOFT of 6 degrees produced nearly double the amount of curve when compared to someone with 14 degrees of SPIN LOFT. I’m not saying long drive competitors need to immediately increase SPIN LOFT, but they should experiment with a slightly higher SPIN LOFT and see if they can still achieve optimal BALL SPEED, SPIN RATE, and LAUNCH. If they can, they may be able to gain more accuracy from a slightly higher SPIN LOFT and keep a few more drives in the grid during competition.
This research leads several conclusions. When looking at why the ball curves, we must also examine SPIN LOFT. We learned that abnormally low SPIN LOFT numbers combined with abnormally high FACE TO PATH numbers can be a bad recipe for control. If this is your situation, we highly recommend minimizing the FACE TO PATH first so you can maintain a low SPIN LOFT. But if results do not improve, you may benefit from increasing SPIN LOFT. This can offer the benefit of reducing SPIN AXIS tilt and less curve in the ball flight. Since a negative ATTACK ANGLE increases the optimal SPIN LOFT, you can learn to hit down on the ball with a driver to gain more accuracy. Also, since an open FACE TO PATH increases the SPIN LOFT, you can learn to play a fade to gain more accuracy. These are two methods I recommend for controlling ball flight curve by increasing SPIN LOFT. I also recommend referencing our SPIN LOFT safety zones for each club in Level 3. This will help you analyze SPIN LOFT more effectively and determine where your SPIN LOFT numbers are on the spectrum. For more information, please review our book for helpful tips on making the appropriate adjustments in your swing.